Switch



May 3, 1955 M. J. DoBEs E-r AL 2,707,734

y, SWITCH Filed ocx. s1, 1951 :s sheets-sheet 1 JNVENTORS MICHAEL .7. DOBES 3 Sheets-Sheet 2 May 3, 1955 M, .L DoBEs ET AL SWITCH VFiled oct. 51, 1951 INVENTORS BY M/CHA E 7. DOB'ES JAMES H. `SMITH U. )I www.

May 3, 1955 M. J. DoBEs ET AL 2,707,734

.SWITCH Filed oct. 31, 1951 s sheets-sheet s BYL-fA/wfs H. sM/TH SWITCH Michael J. Dobes, Euclid, and James H. Smith, Cleve land, Ohio, assgnors to The National Acme Company, Cleveland, Ohio Application October 31, 1951, Serial No. 254,032

Claims. (Cl. 200-70) applied to the switch and travel tolerance be more rig,

idly adhered to.

Our invention is concerned, therefore, with a' switch which, while not limited to usein aircraft, is adalted f or such use by its adherence to the above prescribd con-. ditions. The switch` contains a novel snap actio'device. and contacts which are compact, and light in weight yet I are positive in action, maintaining good contact without chatter even when the switch is subjected to afi'acceleration equivalent to fifty times that of gravity (50 g.). Suflcient overtravel is provided for, by our construction, to avoid breakage of parts because of slight misalignments or the like.

A complete understanding of our invention in its ernbodiment may be had by reference to the following description and figures which form a part of this specication.

Fig. l is a rear elevational view of the switch with the cover removed;

Fig. 2 is a sectional view along line 2--2 of Fig. 3 with parts of the snap action mechanism broken away to show underlying parts;

Fig. 3 is a front elevational view of the switch with the front cover removed;

Fig. 4 is a sectional view along line 4-4 of Fig. 3;

Fig. 5 is a rear elevational view of the snap action lever sub-assembly separate from the rest of the switch,

a part being broken away to show otherwise concealed parts;

Fig. 6 is an elevational view of the driving member separate from surrounding parts;

Fig. 7 is a top plan view of the driving member;

Fig. 8 is a partial elevational view of the slide member and movable contacts removed from their surroundings;

Fig. 9 is an elevational view of the parts shown in Fig. 8;

In aircraft, however, the nature of tlie craft ICC is suicient to snap the driven member from one posltion to a second position. The contacts are of a type which under test has maintained good contact without Y chatter at accelerations of as much as tfty times that of gravity. The movable contact is a sliding type operated by the arcuate movement of the driven member.

More particularly and referring to the gures, our invention comprises a switch enclosed in a housing 10. An operating shaft 11 is journalled in the lower part of the housing extending out from the front thereof. 0n the extending part, an Aopating lever 12 is fixed by any convenient means. i

At the rear of the housing a snap action device is enclosed. This snap action includes a driving member 15 fixed to the shaft 11 by a pin 16. The member 15 (Figs, 6 and 7) is formed with a body part 17 which surrounds the shaft. A necked part 18 extends from the body 17 and carries an arcuate head part 19 symmetrically disposed on both sides of the neck 13. The head is formed with bosses 20 on both front and rear at the outer ends l.leaving a channel 21 between the bosses 20 in the cen- Lit Fig. l0 is a view similar to Fig. 4 of an alternative a housing in which is journalled a shaft. An operating i lever on this shaft turns a driving member. The driving member releases a spring loaded plunger-type latch lcarried by a driven member, by a simple release device, .and then, if necessary, is adapted to engage the driven member to move it positively if the contacts should stick. .Y Normally, a spring engaged between the two members tral part of the arc (Figs. S and 6). An arcuate groove 22 is formed across the head 19 in a direction longitudi- ,nally of .the shaft for a purpose to be made clear hereinafter.

The driven member is in the form of a forked lever V23 having two legs 24 extending through the two channels 21 in the driving member and freely journalled on the shaft 11. These legs are also formed to provide a neck part 25. A torsion spring 26 of substantially C- snape engages both the neck parts and 13, as their sides are co-planar, and thus is adapted to store up energy should there be any relative displacement between the driving and driven members.

At the upper end of the lever 23, the legs 24 are joined together, and at this juncture, the lever is formed with a hole in which a latch stem 28 is slidably journalled. A yoke 29 is formed at the lower end of this stem, and a roller 30 formed with an axle 31 extending across the yoke is journalled in arcuate slots at the end of the yoke. A compression spring 32 engages the top of the yoke 29 and extends around the stem 23 into a hole 35 formed in the lever 23. The spring 32 thus holds the roller 30 against the upper surface'of the head 19, and when the torsion spring 26 is not stressed, the roller 30 is seated in the groove 22. The groove 22 is preferably of arcuate cross section having a larger radius than that of the roller 30 as is best shown in Fig. 5. When the driving vious that the roller 30 and, along with it, the stem 28 will be moved upward away from the shaft which releases a latch as will be described.

A latch member 36 is fixed to the outer end of the stem 28 by any convenient means. This member is formed with a rib 37 extending on both sides of the stem in a direction longitudinally of the shaft 11. This n'b is thus in position to engage a pair of latch plates 3S (Figs. l and 2) fixed to the housing. Notches 39 in the plates 38 are formed to tit the rib and thus while these are engaged, the driven member is held in a xed position relative to the housing. As the driving member 15 is turned by the shaft, however, the roller 30 is pushed upward by the form of the groove 22 until the stem raises the latch member suiciently to disengage the rib.

At this point, the torsion spring 26 is stressed considerably, and therefore there is a force urging the driven lever 23 in the direction of motion taken-by the driving member 15. If this force is not sufficient to start the movement because of welded contacts or other restrictions, the bosses 20 on the head 19 of the driving member will engage the legs 24 after very slight additional movement of the driving member, and there will be a avo '7,734

positive drive from the operating lever 12 to the driven lever 23. After thus starting the action, the spring 26 will snap the lever 23 over to its second position. lt will be obvious that this snap action is not limited to two positions, however, and that many notches 39 could be formed in the plates 3S to provide several positions for the switch.

The housinglt) is formed with shoulders 4.2 adjacent the end of the: head 19 of the driving member. The nearest shoulder is normally spaced from the head by a short distance at the alternate positions of the switch. This allows a certain definite amount of overtravel of the operating lever 12 without breaking any parts and i ts tri ing the switch again. The overtravel is preferably of the oruer`of-2to degreesainnl.switcgh0 of the type shown, but could be more or less if desired.

A small proiecting stem 44 is formed on the front edge of the driven lever 23 and extends inte an elongated socket 45 on the rear of a slide member 46. See Fig. 9.

The member 46 is slidably mounted on a partition wall 47 in the housing 1li. A contact block 48 holds the slide in position against the wall, but allows free lateral siiding action. The socket 45 is formed in a boss 56 projecting from the rear of the slide through an opening in the wall 47. The socket is elongated in a vertical direction to allow some sliding therein of the stem 44 because of its arcuate movement. It is obvious, however, that the arcuate snapping movement of the lever 23 will be translated to a quick horizontal movement of the slide 46 by this device.

The movable contacts are carried by the slide, and in the embodiment shown in Figs. 2-4 and 8 are in the form of a pair of H-shaped plates 52 superimposed and adapted to engage the fixed contacts S3 mounted on the contact block 48. The fixed contacts 53 are wedge shaped and are pointed inwardly towards each other at the plane of the plate S2. These plates are formed with the ends of the legs 51 of the H-shape curved outwardiy from each other so that the wedge shape of the fixed contacts will be engaged between the plates to cam them apart (see Fig. 4). The plates 52 are mounted on a pair of posts 4 on the slide member 46 and are pressed against shoulders 55 by springs 56. A washer 57 or the like may provide an abutment for the outer end of the spring 56. Springs 58 may be used on-the inner side ofthe plates 52, if desired, to assure proper contact between the fixed and movable contacts, and said springs 56 and 58 can be so balanced as to permit the plates 52 to float. It will be recognized by those skilled in the art that my contacts need not be H-shaped but might have three or more contacts. lt is also envisioned that the Hshapcd contacts might be used in pairs or in greater numbers of Because of the contact on both sidesitlixedeonaa. tacts, it is apparent that any force tending to move one 55 movable contact away from the fixed contacts, will press the other more firmly against the fixed Contact. Thus, there is no possibility of chatter because of accelerations in the direction of the axis of the shaft 11, and since the contacts are fixed in the other directions, the switch is 60 virtually shockproof insofar as physical impacts or accelerations are concerned.

Suitable covers 6G and gaskets 6l. may bc held to the housing by screws 62, and a threaded boss 63 may be provided to receive a conduit or fitting (not shown), as 65 is well known in the art.

An alternative form of contact is shown in Figs. lil and ll. In this form, the sli-:ie member 46 is formed with an elongated boss 65 on its front face. A pin 66 extends transversely through the boss 65 and carries 70 the movable contact plates 67. Suitable contact members 68 are fixed to the plates and are adapted to contact the fixed contact members 69 mounted on the contact block 48. A pair of compression springs 70 extending fi plates 67 near the contact members 68 to press them resiliently against the fixed contacts. This type of contact is adequate for normal use although not so satisfactory as the preferred device in the resistance to high accelerations and impact.

Having thus vdescribed our invention, we are aware that numerous and extensive departures may be made from this invention without departing from the spirit or scope therefrom.

We claim:

l. A snap action comprising a housing, a shaft journalled in said housing, and a driving member fixed to said shaft having a head formation extending away from said shaft, a lever journalled on said shaft, latch means slidably journalled in said lever and releasably engaged by cam means formed on said head formation, at least one latch plate fixed in said housing having means rclcasably engaged by said latch means in a plurality of predetermined positions, said cam means being formed to release said latch means when said driving member is displaced relative to said lever, and spring means engaged between said driving member and said lever to store energy upon relative displacement therebetween and functioning to snap said lever toward said driving member when said latch is released.

2. A snap action comprising a housing, a shaft journalled in said housing, and a driving member fixed to said shaft having a head formation extending away from said shaft, a lever journalled on said shaft, latch means slidably journalled in said lever and releasably engaged by cam means formed on said head formation, at least one latch plate fixed in said housing having means releasably engaged by said latch means in a plurality of predetermined positions, said cam means being formed to release said latch means when said driving member is displaced relative to said lever, spring means engaged between said driving member and said lever to store energy upon relative displacement therebetween and functioning to snap said lever toward said driving member when said latch is released, and shoulders formed in said housing adjacent said driving member and in spaced relation to said head formation in any of its plurality of predetermined positions, said shoulders engaging said head formation when the relative displacement between said driving fmember and said lever is greater than that required to operate said latch means.

3. A snap action comprising a housing. a shaft journalled in said housing, and a driving member fixed to said shaft having a head formation extending away from said shaft, a.lever journalled on said shaft, latch means slidably journalled in said lever and releasably engaged by cam means formed on said head formation. at least one latch plate fixed in said housing having in ns rcleasably engaged by said latch means n a plurality 'of predetermined positions, said cam means being formed to release said latch means when said driving member is displaced relative to said lever, and Spring means: er:- gaged between said driving member and said lever to store energy upon relative displacement therebetween and functioning to snap said lever toward said driving member when said latch is released, a partition wall in said housing adjacent said lever having an opening therethrough, said lever having a boss extending toward said wall, a slide member slidably disposed on said wall epposite said lever, a boss having an elongated slot formed on said slide member on the side adjacent said lever and extending into said opening, said boss on said lever c1:- tending into said elongated slot providing a coupling therebetween, fixed contacts mounted in said housing and rnovablecontaets mounted on said slide member, said slide member being movable laterally through said coupling by arcuate motion of said lever to carry said movable contacts into and out of engagement with said fixed contacts.

through holes in the boss 65 are engaged between the 75 4. A snap action for a switch comprising in combination, a housing, a shaft journalled in said housing, a driving member Xed to said shaft, said member having an arcuate head formation substantially concentric with said shaft, a lever having legs journalled on said shaft on each side of said driving member, said head formation being' thereby disposed between said legs, latch means slidably Journalled in said lever and extending between said legs, cam means formed on said head formation engaging said latch means, a pair of latch plates mounted in said housing, one of said plates being on each side of said latchl means, said plates and latch means being formed with releasably engaging complementary ribs and notches, said cam means being formed to operate said latch means to release it at a point of predetermined displacement between said lever and said driving member, and spring means engaged between said driving member and said lever to store energy upon relative displacement therebetween, and functioning to snap said lever to an alternate position when said latch means is released by the movement of said driving member to its point of predetermined displacement.

5. A snap action for a switch comprising in combination, a housing, a shaft journalled in said housing, a driving member fixed to said shaft, said member having an arcuate head formation substantially concentric with said shaft, a lever having legs journalled on said shaft on each side of said driving member, said head 5 formation being thereby disposed between said legs, laterally extending bosses at each end of said head formation adapted to engage said legs for positive movement thereof as said head is moved, said bosses being spaced apart far enough normally to allow spring pressed operation of said switch, latch means slidably journalled in said lever and extending between said legs, cam means formed on said head formation engaging said latch means, a pair of latch plates mounted in said housing, one of said plates being on each side of said latch means, said plates and latch means being formed with releasably engaging complementary ribs and notches, said cam means being formed to operate said latch means to release it at a point of predetermined displacement between said lever and said driving member, and spring means engaged between said driving member and said lever to store energy upon relative displacement therebetween, and functioning to snap said lever to an alternate position when said latch means is released by the movement of said driving lever to its point of predetermined displacement.

References Cited in the tile of this patent UNITED STATES PATENTS 2,369,964 Goff Feb. 20, 1945 2,431,929 Goi Dee. 2, 1947 2,468,551 Goif Apr. 26, 1949 2,523,370 Jeffrey Sept. 26, 1950 

